Electrical discharge device employing a pool-type cathode



ELECTRICAL DISCHARGE DEVICE EMPLOYING A POOL-TYPE CATHODE Filed Nov. 20, 1946 I Inventor: Howard E. zuver's,

I Wit, EIZZMQJ Y His Attorney.

Patented Mar. 2, 1 948 ELECTRICAL DISCHARGE DEVICE EMPLOY- ING A POOL-TYPE CATHQDE Howard E. Zuvers, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Application November 20, 1946, Serial No. 711,144

My invention relates to electric discharge devices -employing a pool-type cathode and particularly to an improved baiile construction for devices of this type.

In the design of electric discharge devices having pool-type cathodes, it is a problem to provide a Structure which adequately deflects liquid particles originating on the cathode from the region of the anode and which does not increase the arc drop to an unreasonable value. In accordance with an important aspect of my invention, I provide an improved batlle structure which prevents practically all of the liquid particles liberated from the cathode from reaching the anode region. At the same time, the opposition offered to the arc discharge by the baffle is not so great as to increase the arc drop appreciably. The battle structure is also suitable for functioning as a control electrode.

It is an object of my invention to provide a new and improved electric discharge device of the gas-filled type.

It is a further object of my invention to provide an improved electric discharge device having a pooltype cathode which is characterised in its operation b relative freedom from are backs, and a reasonablylow arc drop.

My invention will be better understood by reference to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims. In the drawing, the single figure is an e1eva- 'tional view partially in section of an electric discharge device embodying my invention.

Referring now to the drawing I have shown, my invention embodied inan 'electric discharge device of the ignitron" type and including an elongated cylindrical envel p l preferably formed of steel. The envelope is closed at its upper end by a: header assembly including an anode seal, designated by the numeral 2, for supporting a generally cylindrical anode 3 centrally within the upper end of the envelope. As is well 6 Claims. (01. 250-275) ducting liquid 1 which to advantage may be mercury. In the operation of devices of this characteran arc discharge is established between the surface of the cathode and the anode 3. For this 1 purpose, a starting electrode 8, which in the illus trated embodiment is of the immersion-ignitor type, is provided. The starting electrode i supported from the header in insulated relation with respect thereto by a suitable lead-in seal including an elongated body of glass 9 which is sealed to an eyelet l0 securedin the header 6, and which surrounds a lead-in conductor II.

As will be readily appreciated by those skilled in the art, considerable difiiculty is experienced in providing discharge device of this character which are relatively free from are back and, at the same time, have a sufficiently low arc drop to render'them satisfactory for heavy current car-. rying duty. In accordance with an important aspect of this invention, I provide an improved bafiie structure or enclosure, which surrounds the region of the cathodein which the starting electrode is immersed. This structure is arranged to intercept practically all liquid particles which are liberated from the cathode during operation of the device, but not to interfere appreciably with the establishment of an arc discharge from the cathode to the anode. Asillustrated the baflie structure is supported from the header 6 on a plurality of studs l2, which are supported in insulated relation about the central portion of the header by means of cylindrical insulators l3.

These insulators are secured to the header 6 by means of stud I4 which are welded to the inner surface of the header. Three such insulators l3 and mounting studs l2 are employed in the particular embodiment of my invention illustrated in the vdrawing. The baffle is made up of a plurality of ring-like members [5 which are stacked on the studs l2 and suitably spaced by spacer members IS. The bafiies and spacers are formed of a suitable material which may be predominately graphite. The upper end of the generally cylindrical assembling provided by the baillemembers I5 is closed by a disk-like member l1 having a marginal position l8 conforming in shapeto the ringlike members l5.- The stack of baffle members and spacers is secured in assembled relation by nuts I9 threaded on the upper end of the studs l2. and engaging suitable bosses provided on member H. The baflle members l5 may be considered "as having frusto-conical surface, and the spacing of the members is preferably such that the projections'of the individual members on the axis of the envelope 1 are overlapping. In other words, there is no unobstructed radial path from the interior of the bafile structure to the exterior thereof and all the passages provided by the structure are directed away from the anode. The structure provided by member l and I1 ma be considered as an inverted cup-shaped louvered baffle.

In order that the bafile structure may be maintained at a suitable voltage with respect to the cathode and, if desired to function as a control electrode, a suitable lead-in conductor 20 is provide-d. This conductor is sealed through the envelope in insulated relation with respect thereto by a suitable glass bead 2 l, and is connected at its upper end to the baiiie structure by means of a terminal 22 which is assembled in the stack on one of the mounting studs l2. A cylindrical ring 23 positioned within the insulators I3 is secured, to the header 6 by suitable straps 24. The ring may be formed of a refractory material such as molybdenum and extends above the cathode surface to prevent impurities collecting on the surfacefrom entering the region of the starting electrode 8. The ring 23 also tends to minimize the motion of the cathode as a result of shock or vibration of the tube envelope.

In operation of the device a cathode spot is formed on the surface of the cathode by passing a current through the electrode 8 which exceeds a critical minimum value. If the volta e impressed on the anode 3 is more positive than the voltage of the cathode I by a predetermined amount, an arc discharge is established between the cathode spot and the surface of the anode. When the anode cathode voltage reverses it is essential that the space within the envelope l and particularly the region near the anode be deionized rapidly so that an arc will not become established in the inverse direction. The baflie structure which I provide in accordance with my invention prevents liquid particles of mercury from collecting on the anode surface or from accumulating in the region of the anode and as a result deionization takes place quickly and the tendency for are backs to occur is minimized. The baflie structure is at the same time sufliciently open so that the arc drop is not too high.

While I have described and illustrated a particular embodiment of my invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention in its broader aspects and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

An electric discharge device including an envelope, a pool-type cathode retained within said envelope, an anode supported within said envelope in insulated relation with respect to said cathode, means for forming a cathode spot on the surface of said cathode, and a baffle structure surrounding said last-mentioned means and comprising a plurality of generally annular members each having a frusto=conioal surface, said membersbeing supported in a stack. in such mutually spaced relation that the projections of said members on a plane extending longitudinally of the stack are overlapping and a member presenting a substantially continuous transverse surface supported between said stack and said anode.

2. An electric discharge device including an envelope, a pool-type cathode retained within said envelope, an anode supported within said envelope in insulated relation with respect to said cathode, means for forming cathode spot on the surface of said cathode and a baflle structure surrounding said last-mentioned means and comprising a plurality of apertured baffle members each having a sloping surf-ace, said members being supported in a stack in mutually spaced relation with said surfaces extending outwardly and downwardly, said stack providing a hollow structure opening toward said anode, and means substantially closing the end of said stack facing the anode.

3. An electric discharge device including an envelope, a header fol-said envelope for retaining a pool-type cathode Within said envelope, an anode supported within said envelope in insulated relation with respect to said cathode and in opposed relation to said header and an inverted cup-shaped louvered structure supported on said header.

4. A header assembly for an electric discharge device of the pool-type comprising a metal header, a starting electrode supported from said header in insulated relation thereto, and a hollow baffle structure supported from said header and surrounding said electrode, said baffle being provided with a plurality passages through the side walls thereof, the walls of said baflie structures having substantial thickness and said passages being so directed downwardly toward said header so that all particles traversing said passages in an outward direction are directed toward said header.

5. An electric discharge device comprising an elongated cylindrical envelope, an anode supported from one end of said envelope, at liquid cathode positioned at the other end of said enve=- lope in insulated relation with respect to said anode, means .for forming a cathode spot on the surface of said cathode, a baffle structure interposed between said anode and the region of said cathode including said spot, said baffle structure including a plurality of generally annular members of dished configuration supported in spaced relation and a member at the upper end of the stack providing a substantially continuous surface arranged in opposed relation with respect to the end of said anode, and a lead-in conductor sealed through said envelope and connected with said bafile structure.

6. An electric discharge device comprising an elongated cylindrical envelope, an anode supported from one end of said envelope, a liquid cathode positioned at the other end of said envelope in insulated relation with respect to said anode, means for forming the cathode spot on the surface of said cathode and a hollow cuplike louvered baflle structure interposed between said anode and said cathode with the closed end thereof facing said anode, the side wall of said structure having substantial thickness and provided with a plurality of openings directed away from said anode.

HOWARD E. ZUVERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,249,485 Miles July 15, 1941 FOREIGN PATENTS Number Country Date 508,722 Great Britain July 5, 1939' 

